The .25 Winchester Super Short Magnum is a third member of the Winchester Super Short Magnum (WSSM) cartridge family created by Winchester and Browning. It is the largest caliber of the WSSM line (excluding wildcats) and is the most capable of handling large game such as deer and wild boar.

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.25 WSSM
25 WSSM cartridges loaded for an AR-15 magazine. For comparison, a 2 3/4" shotgun shell & 5.56mm NATO cartridge are included
Type	Rifle
Place of origin	USA
Production history
Designer	Browning / Winchester
Manufacturer	Winchester
Produced	2004–present
Specifications
Parent case	.300 WSM
Case type	Rimless, bottleneck
Bullet diameter	.257 in (6.5 mm)
Land diameter	.250 in (6.4 mm)
Neck diameter	.305 in (7.7 mm)
Shoulder diameter	.544 in (13.8 mm)
Base diameter	.555 in (14.1 mm)
Rim diameter	.535 in (13.6 mm)
Rim thickness	.054 in (1.4 mm)
Case length	1.670 in (42.4 mm)
Overall length	2.362 in (60.0 mm)
Primer type	large rifle
Maximum pressure (transducer)	65,000 psi (450 MPa)
Ballistic performance
Bullet mass/type Velocity Energy 75 gr (5 g) VMax 3,775 ft/s (1,151 m/s) 2,374 ft⋅lbf (3,219 J) 85 gr (6 g) BT 3,547 ft/s (1,081 m/s) 2,375 ft⋅lbf (3,220 J) 100 gr (6 g) BT 3,264 ft/s (995 m/s) 2,366 ft⋅lbf (3,208 J) 115 gr (7 g) BT 2,999 ft/s (914 m/s) 2,297 ft⋅lbf (3,114 J) 120 gr (8 g) SP 2,985 ft/s (910 m/s) 2,375 ft⋅lbf (3,220 J)
Source(s): Hodgdon Online Reload Data

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It is a necked-up version of the .243 WSSM,^[1] which is in turn a shortened .300 WSM (Winchester Short Magnum). The WSSM cartridges are based on ballistics design philosophies that are intended to produce a high level of efficiency.^[2]

Like the other WSSM rounds, the .25 is effectively a magnum in name, and energy-per-COAL, only. Performance wise it is nearly identical to the long action .25-06 Remington, making it well suited for medium to large game with the advantage of being usable by lighter short action rifles.^[3] Having the short fat design, the cartridge loads potentially burn at a more consistent rate, in theory providing a lower muzzle velocity standard deviation (SD) for increased accuracy. Performance is far less than true .25 caliber magnum rounds such as the .257 Weatherby Magnum. In fact, ballistically it's almost identical to the improved version of the .257 Roberts, which P.O. Ackley said was his favorite choice for an all-around cartridge.^[4]

• .223 WSSM
• .243 WSSM
• .257 Roberts
• .25-06 Remington
• Winchester Super Short Magnum
• Table of handgun and rifle cartridges
• sectional density